Weight transfer system



Sheet 1 of 4 Filed March 30, 1967 Pier a 17526 arcison March 4, 1969 P.F. RICHARDSON WEIGHT TRANSFER SYSTEM Filed March 30, 1967 March 4, 1969P. F. RICHARDSON 3,430,984

WEIGHT TRANSFER SYSTEM Filed March so. 1967 Sheet 3 of 4 J72 z nforxPie?" 2 F'CI 70 8072 March 4, 1969 P. F. RICHARDSON WEIGHT TRANSFERSYSTEM Sheet Filed March 30. 1967 United States Patent 3,430,984 WEIGHTTRANSFER SYSTEM Pierce F. Richardson, Oakbrook, Ill., assignor toInternational Harvester Company, Chicago, Ill., a corporation ofDelaware Filed Mar. 30, 1967, Ser. No. 627,077

US. Cl. 280-405 Int. Cl. B60d; B62d 53/00; Afllb 63/112 1 Claim ABSTRACTOF THE DISCLOSURE Background of the invention This invention relates toimplement-attaching hitch mechanisms for agricultural tractors having adraft and position control system of the type wherein the draft load isbalanced against a force-resisting and yieldable means, generally in theform of a spring, and power lift mechanism is actuable responsive tovariations in the draft load for adjusting the working depth of anattached implement in consonance with such variations, and which isinde-' pendently responsive to a manually controlled device for varyingthe vertical elevation or position of an attached or trailed implement.A hitch of this type is generally operative in the draft control rangethereof to maintain constant the compressive or tensile load on saidhitch mechanism, and operates to change the position into which it hasbeen set when the compressive or tensile load thereon is changed, and isusually associated with a draft and position control system which may beof the type described, for instance, in the United States Patent No.3,132,699 issued to Andrew Brudnak, Jr. and Herbert G. Akins.

As is well known mechanisms of this type have heretofore been proposedand utilized for effecting draft control with mounted or semi-mountedimplements but were not equally adaptable for implements or vehicles ofthe trail behind type. The term trailed equipment as used hereindesignates a vehicle or implement attached to a tractor and trailedalong the ground behind the tractor on wheels or other ground engagingmeans and having at least part of its own weight carried by the groundengaging means. One of the earliest known arrangements utilizing a draftcontrol and hitch linkage arrangement for accomplishing a weighttransfer type of operation with trailed equipment was disclosed in theWultf et al. United States Patent No. 3,062,561 issued Nov. 6, 1962. Thearrangement shown therein, however, is not adaptable for a great varietyof types of trailed implements and, furthermore, requires an additionaldrawbar connection for attaching the trailed equipment directly to thevehicle rather than through the links of the hitch linkage mechanism.Subsequent to this disclosure other arrangements have been proposed forthe same purpose but most such devices are believed to be somewhatcomplicated, cumbersome and costly to fabricate and hence would not seemto be altogether satisfactory.

Summary of the invention The present invention is more specificallydirected to Ice the utilization of a hitch mechanism of the typeheretofore noted for effecting the transfer of weight from a trailedvehicle or implement to a tractor to avoid slipping of the tractor drivewheels on the ground. In the invention as proposed the hitch mechanismis subjected to a load dependent on the amount of the weight it isdesired transferred being maintained irrespective of whether the tractorchanges its position of inclination or position of height relative tothe trailed vehicle. The invention proposed herein offers the advantageof being able to maintain weight transferred independent of any changedposition in the inclination of a tractor relative to the trailedequipment. Furthermore, this transference of a predetermined amount ofweight is automatically accomplished once the mechanism is pre-set forthe desired weight transfer. Additionally, such weight transferoperation may be performed by means of a generally conventional draftand position control system wherein the associated hitch linkagemechanism is readily modified by the addition of a simple adapter orframe assembly. Another advantage it offers is that the trailedequipment may be connected directly to the links of the hitch linkagemechanism without having to be otherwise directly connected to thetractor through an added drawbar connection. A further advantage isfound in the feature that it is more universal in application since itmay be utilized with a greater variety of types of trailed equipment,and is, of course, readily adaptable to conventional hitch linkagemechanisms. Furthermore, the arrangement as proposed provides a form ofsafety feature in that backward tilt of a tractor is limited when thetractor is so equipped.

The principle object, therefore, of the present invention is to providean improved mechanism for attaching trailed equipment to the hitchmechanism of a tractor whereby a predetermined amount of weight istransferred from the trailed equipment to the tractor irrespective ofthe position of inclination of the trailed equipment relative to thetractor.

Another object is to provide a frame assembly mounted on the outboardends of the links of an implementattaching hitch mechanism of a tractorfor permitting the use of such mechanism for attaching trailed equipmentto the tractor and for permitting the transference of a predeterminedamount of weight from the trailed equipment to the tractor.

A further object is to provide an adapter or frame assembly readilymountable on the links of an implement attaching hitch linkage mechanismso as to accommodate an associated draft control system in providingpre-selectable transfer of weight from a trailed implement to thetractor trailing such implement.

A still further object is to provide a means of improving traction bytransferring weight to the drive wheels of a tractor from trailing orsemi-trailing equipment wherein the tractor is equipped with a draft andposition controlled three-point hitch with either upper or lower linksensing.

A more specific object is to provide an adapter, shaped to resemble aninverted Y, which is attached to the three links of a hitch linkage andincludes a swing boom pivotally mounted thereto while the outboard endof said boom provides an attaching point for a chain or link attached tothe trailed equipment by way of tongue of said equipment.

A still further specific object is to provide an inverted Y shapedadapter frame assembly, adapted for attachment to the upper and lowerlinks of an implement attaching hitch linkage mechanism on a tractorvehicle, and including a swingable boom pivotally mounted thereon andhaving a resiliently yieldable link connected between an outboard end ofsaid boom and the tongue of a vehicle being trailed by the tractor.

Other objects and advantages will be understood and will become moreapparent from the following description when read in conjunction withthe accompanying drawlngs.

Description of the drawings FIGURE 1 is a side elevational view of atractor and an attached tillage trail behind implement and embodying theproposed invention;

FIGURE 2 is a view similar to FIGURE 1 but showing the application witha transport trail behind vehicle;

FIGURE 3 is a fragmentary side elevational view of the rear portion ofthe tractor of the preceding views, schematically showing the power liftsystem and wherein the draft and position control system is shown inassociation with an upper link sensing hitch mechanism;

FIGURE 4 is a view similar to FIGURE 3 but showing the controls systemsin association with the lower link sensing of a hitch mechanism;

FIGURE 5 is a perspective view of a fragment of the rear portion of atractor with the adapter or frame assembly of the proposed inventiontherein;

FIGURE 6 is a rear end View, on an enlarged scale, of the proposedadapted assembly looking toward the front end of the associated tractor;

FIGURE 7 is a side elevational view, on an enlarged scale of theproposed adapted assembly; and

FIGURE 8 is a vertical sectional view of the proposed resilient link forconnecting the adapted to the tongue of a trailed vehicle.

Description of the preferred embodiment Referring now to the drawings,it will be seen that the arrangement selected for depicting a preferredform or application of the invention includes a tractor vehicle 10having a frame indicated in its entirety by the reference numeral 11 andhaving at its front end a steerable wheel assembly 12 and at the rearportion thereof a housing assembly 13 which supports in conventionalfashion a pair of laterally spaced traction wheels 14.

The tractor has associated therewith a power lift unit means, showndiagrammatically as portions of FIGURES 3 and 4 and indicated generallyby the reference numeral 15, which may be suitably mounted and carriedby the tractor frame 11 as is well understood. This unit may include inassociation therewith a suitably journalled rockshaft 16, a cylinder 17having a piston 18 therein joined by a connecting rod 19 to a crank arm20 constrained for rotation with said rockshaft, and a pair of laterallyspaced lift arms 21, 21 mounted on opposite ends of said rockshaft andsuitably secured thereto for rotation therewith. Said lift arms areconnected by lift or drop links 22, 22 to respective lower draft links23, 23 which latter links, in turn, are pivotally connected at theirforward ends to the rear portion of the tractor, as indicated at 24, topermit conventional vertical and slingable movement thereof. An upper ortop draft link 25 is connected at its forward end to the tractor andtogether with the lower links 23, 23 comprise what is commonly termedimplement-attaching linkage mechanism'or draft means for effecting adraft or load connection between the tractor and an implement beingborne or trailed by the vehicle.

The hitch mounting means constituting the support for the forward end ofthe uppei link 25 on the tractor incorporates therein, in onearrangement of the linkage mechanism, the force-resisting and yieldablemeans represented by the torsion bar assembly indicated generally at 26.Since a device of this type is specifically disclosed in US. Patent No.3,241,620 issued to Andrew Brudnak, Jr., reference may be had theretofor further details of the construction and operation thereof. Sufficeit to say that the link 25 is pivotally attached to a lever assembly 27,an oppositely extending portion of which is pivotally connected to amotion-transmitting draft responsive to control linkage connection 28,and while said lever assembly 27 is pivotally mounted on the tractor itis also connected to one end of a torsion bar member 29 of assembly 26the opposite end of which bar is anchored against rotation to thetractor frame 11 by suitable anchoring means such as indicateddiagrammatically at 30. In the linkage arrangement shown in FIGURE 4 theupper link 25 is pivotally connected to the tractor, as indicated at 31,while the lower links 23, 23 are connected to a lever assembly 27a, oftorsion bar assembly 26a, with the oppositely extending portion of saidlever assembly connected to the draft responsive control linkage 28a,and the torsion bar 29a, is suitably anchored to the frame as indicatedat 30a. The construction of the torsion bar arrangement for the lowerlinks is detailed in US. Patent No. 3,239,013 issued to Kurt E. Hansmannand reference may be had thereto for further details of the constructionand operation thereof.

The induced motion constituting the signal produced as a result ofmovement of the control linkage 28 by the draft link 25, in oneinstance, and the draft links 23, 23 in the other instance, is useablytranslated to control the power lift unit 15 by coordinated actuation ofan actuator or control valve means such as 32. The latter actuator orvalve may be connected by a conduit 33 with the ram cylinder 17 and byconduit 34 with the suction inlet of a hydraulic pump 35, while aconduit 33a connects the discharge outlet of the pump with the ramcylinder by way of conduit 33. A further conduit 36 connects saidactuator valve with a fluid reservoir such as indicated at 37. A pistonelement 39 in said actuator valve has a biasing or centering spring 39associated there-with for apurpose which will be understood as thedescription proceeds. A valve actuating member in the form of aconnecting rod 40 connected to said piston element has a transverse pinor abutment stop member on the outer end thereof as shown at 41. Theinner end of control linkage connection 28 is pivotally connected at 28bto a link or lever 42 intermediate the ends thereof and one end of saidlever is positioned for abutment with the transverse pin member 41 whilethe opposite end is pivotally connected to a push rod or forcetransmitting link indicated at 43, that, in turn, is connected by acontrol lever, such as 44, to a pivotally mounted manual control handle45.

Pivotally connected at 40a to the valve actuating member or connectingrod 40, intermediate the piston 38 and the point of engagement of lever42 with the abutment stop or pin 41, is a link member 46 the oppositeend of which is slotted at 47 to slidably accommodate one end of awalking beam member 48. The opposite end of said walking beam ispivotally connected to a push rod or connecting link indicated at 49,that, in turn, is connected by a control lever, such as 50, to pivotallymounted manual control handle 51. The walking beam 48 intermediate theends thereof is pivotally connected to a differential crank member 52 ata point such as 48a intermediate the ends of the crank and offset from aline extending between the ends of said crank. One end of the lattercrank is pivotally mounted at 52a on the frame 11 while the opposite endis pivotally connected to a link 53 and the opposite end of the latterlink is pivotally connected to a crank arm 54 secured to and constrainedfor rotation with rockshaft 16. The linkage mechanism associated withand actuated by the control handle 51 is commonly termed the positioncontrol linkage system while that associated with the control handle 45is generally termed the draft or load control linkage system.

Since the foregoing power lift unit together with the associatedposition and draft control systems are described in somewhat greaterdetail in the above noted Brudnak et al. Patent No. 3,132,699 a morecomprehensive description of the details thereof is omitted and only agenerally simplified or skeletonized embodiment or form of these systemsis illustrated and described herein. It will be seen by reference to thedrawings hereof that the power lift and control systems shown in FIGURE4 are substanti-ally identical to those illustrated in FIGURE 3 andhence the same reference numerals are applied to like elements in bothfigures, the suffix a being used to differentiate therebetween.

Now in accordance with the more specific teachings of the presentinvention an adapter or frame-like assembly 55 is provided foraffixm'ent to the outwardly projecting ends of the upper and lower linksof the hitch linkage mechanism so as to accommodate the attachment oftrailed equipment, such as a vehicle or implement, to the tractor. Asillustrated in one preferred embodiment thereof the adapter may comprisea lower cross bar member 56 having upwardly turned end portions 57, '57which receive in overlying relationship an upper cross bar member 58having downwardly turned end portions 59, 59 which are fixedly securedto the upturned ends by suitable aflixing means such for instance as thebolt and nut means indicated at 60. It will be appreciated, of course,teachings hereof. Suitable pivotable connections, such as Welding,riveting, brazing or the like may be used for securing the respectiveend portions together, or, if desired, the upper and lower cross barsmay be fashioned as an integral frame unit, without deviating from anyteachings hereof. Suitable pivotable connecitons, such as the pins 61,may be provided for attaching the frame to the lower links 23, 23 and ifdesired, said pins may be fashioned as extensions of the bolt fasteningmeans 60, or as the pivot pins conventionally provided on the outer endsof lower draft links for attaching equipment to the linkage mechanism.An upper pintle pin or pedestal-like bearing mast 62 fixedly mounted onthe upper cross bar member 58 intermediate the opposite ends thereof hasits upper end fixedly mounted in a coupling or fastener 63 which, inturn, is pivotally attached by suitable removable pin means 64 to theoutward or rearwardly projecting end of the upper link 25. Pivotallymounted on the pin or bearing mast 62 is a boom-like member 65 whichextends rear-wardly therefrom and is swingable in a transverse planegenerally parallel to the ground.

Generally, trail behind vehicles or implements are provided with aconventional form of rigid tongue member, such as represented at 66,that is pivotally attached at one end of the tongue to the assicoatedvehicle or implement in a manner such as to be swingable in a horizontalas well as a vertical plane. The opposite or forwardly extending end ofsaid tongue may be provided with a bifurcated clevis-like clamp orcoupler 67 having aligned apertures in opposite arms thereof adapted toreceive a removable fastener such as the pin 68. The latter pin may beinsertably positioned in aligned apertures in conpler 67 and in aregistering aperture 69' in cross bar 56, intermediate opposite endsthereof, for the purpose of attaching the trailed equipment in a freelys-wingable relation to the pulling or driving tractor vehicle. Usuallythe removable pin 68 is of such dimension with respect to its associatedregistering apertures that a loose fit results and a very limitedvertical movement of the tongue relative to the tractor is tolerated.

A connecting link or hanger member 70 is pivotally connected at one endof said member to the boom member 65 by way of a removable pin 71positioned over the top thereof and insertably receivable in alignedapertures in opposite arms of a U-shaped strap or bracket 72 affixed toone end of said link, while the opposite or lower end of said link ispivotally connected to the tongue 66 by a removable pin 73 insertablyreceived in apertures in a pair of spaced straps or a bracket 74 aflixedto said tongue and in a pair of straps or legs 75 affixed to said link.It will be appreciated however, that other suitable hanger straps orclamping means may be provided in lieu of the illustrated arrangementfor pivotally attaching the link to the tongue.

One preferred form of link 70 comprises a hollow body or casing 76having a transverse member 77 fixedly secured, by suitable means such,for instance, as the welds 78, in one end of said casing and having anopening 79 therein adapted to slidably accommodate a push-pull member 80extending therethrough. The outwardly projecting end of member 80 isfixedly attached to the bracket 72 by suitable means such as the weldsindicated at 81. An aperture 82 in member 80 is provided for receiving aremovable lock-out bolt or pin 83 which is insertably received in saidaperture and in aligned apertures 84, 84 in spaced ears 85, 85 suitablyaflixed to transverse member 77 on opposite sides of the opening 79therein. Positioned within casing 76 is a spring 86 one end of which isdisposed in abutting relation with the transverse member 77 'while theopposite end of the spring abuts an additional transverse member 87having an aperture 88 for slidable accommodation of the push-pull member80 therein. A suitable abutment or stop such, for instance, as the boltand nut means 89 is provided proximate the end of member 80 to supporttransverse member 87 in a seating relation with one end of spring 86. Inorder to fixedly posit-ion the link 70 longitudinally on the boom andprevent said link from normally slipping off said boom a transverselyextending bar-like projection or rail member 90 is suitably fashioned onthe upper surface of said boom and the pin 71 disposed for contactingengagement therewith. In an emergency, however, such as in event of thetongue breaking away from the adapter, the link 7 0' would readily slipor ride up over the projection stop 90 and thereby effect completeseparation of the trailed equipment and thus prevent possible damage tothe equipment or the tractor.

The boom 65, which may be fabricated in any suitable manner, asillustrated herein comprises a central hollow body portion that may befashioned from an inverted U-shape in cross-section beam member 91, anda hub-like bearing member 65a suitably afiixed to one end of said bodyportion and having a central longitudinally extending bore thereinadapted to rotatably receive the pintle pin or mast 62.

In the event the safety feature, provided incident to the use of a rigidconnecting link between the boom member and tongue whereby an excessiveamount of accidental rearward tilt of the tractor is prevented, is not,because of the type or size of equipment being trailed or for otherreasons, of paramount importance a flexible connection such as a chainor cable may be utilized in lieu of said connecting link between theboom and tongue without deviating from any of the inventive conceptshereof.

It will be seen, of course, that by removing the lock-out pin 83 thelink 70 becomes a yieldable and resilient member instead of a rigid linkconnection for purposes which subsequently will be discussed.

Now in order to understand the operation of the present inventionreference is had to the drawings hereof where it will be seen thatmovement of the draft control handle 45 in a direction that rotateslever 42 counterclockwise (FIGS. 3 and 4) about its pivot with linkage28 causes said lever to ultimately engage pin 41 and through valveactuating member 40 moves piston 38, of valve 32, leftwardly against thereaction of spring 39 therein whereupon the pump 35 is placed incommunication by way of conduit 36 with the fluid reservoir 37 and fluidis then delivered under pressure through conduits 3 3a and 33 to thelift cylinder 17. Upon receipt of fluid in cylinder 17, piston 18 ismoved leftwardly and acting through its connecting rod 19, crank arm 20,rockshaft 16 and lift links 21, 21 and 22, 22 raises the hitch linkagemechanism. Upon completion of the lifting movement handle 45 may bemanually returned to neutral with valve 32 likewise returning to neutraland fluid remaining locked in the circuit, or if a draft responsivesignal is received in linkage 28 lever 42 may be forced to pivot aboutits pivotal connection with link 43 and thus permit valve 32 to bereturned to a neutral position by reaction of spring 39.

Upon movement of position control handle 51 in a direction that rotateswalking-beam 48 counterclockwise about its pivot connection with thedifferential crank member 52, the link member 46 is moved leftwardlyagainst the reaction of spring 39 whereupon pump is placed incommunication by way of conduit 36 with fluid reservoir 37 and fluid isthen delivered under pressure through conduits 33a and 33 to liftcylinder 17 to effect a raising of the associated linkage mechanism.When the linkage has been raised to a desired elevation the valve 32 isreturned to neutral either by way of handle 51 or the follow-up linkageindicated by the interconnected members comprising crank arm 54, link53, and differential crank 52 as is more fully explained in the abovenoted Brudnak et al. US. Patent 3,132,699.

Assume initially that the tractor involved is one wherein the torsionbar assembly is actuated by the upper draft link, as illustrated inFIGURE 3, and the trail behind agricultural implement attached is a diskharrow such as depicted in FIGURE 1 and designated generally by thereference numeral 92. In this instance the tongue 66 thereof is attachedby pin 69 to the cross-bar 56, of adapter 55, and the link 70 isinterconnected as a rigid link between boom member 65 and said tongue.Now the handle is set to a predetermined position correlated with thepoint at which a draft responsive signal in linkage 28, resulting from achange in inclination or position of height of the tractor relative tothe trailed implement, becomes effective to actuate the valve 32 andlift or lower the hitch linkage mechanism correspondingly. Assume, forinstance, the tractor wheels encounter soft or loose earth and tend tosink into the ground whereupon the trailed implement will pivot upwardlyabout the lower pivotal connection of adapter with the lower links 23,23 and by so doing induce a compressive force in the upper draft link 25and through the torsion bar assembly 26 effects a leftward movement oflinkage 28. Since the position of lever 42 has been pre-selected, byoperation of handle 45, to engage pin 41 upon movement of linkage 28responsive to a predetermined change in draft or load when this has beenattained the valve 32 will be actuated to lift the linkage mechanism andthereby transfer a portion of the trailed implement weight to thetractor to increase the ground engaging friction of the tractor wheelsand thus prevent the slipping thereof. As conditions are such as topermit the relative inclination or position of the tractor relative tothe implement to be normalized the valve 32 will then be actuated by thespring 39 therein to lower the hitch linkage and return the system toits previous normal condition. In the event the tractor is elevatedrelative to the trailed implement a tensive force is created in theupper draft link 25 and the valve 32 is actuated to effect acorresponding temporary lowering of the hitch linkage and the systemwill be returned to normal when the relative relationship between thetractor and implement returns to normal.

Assume now a trailed implement with a tractor wherein the torsion barassembly is incorporated in the lower draft links 23, 23. In thisinstance the upper draft link 25 is pivotally connected to the tractorand the reactive force resulting from a change in relationship betweenthe tractor and the implement is reflected in the lower draft links andthrough the torsion bar assembly 26a and control linkage 28a to theactuator valve 32 to accomplish the action heretofore explained for anupper link sensing mechanism. In the lower link sensing mechanism itwill be appreciated the forces acting on the torsion bar assembly willbe in a direction reverse from that of the upper link device hence thereversal of direction in movement of the sensing signal is accommodatedin the linkage 28a as illustrated in the Kurt E. Hansmann US. Patent No.3,239,013.

Assume next that the tractor involved has an upper link sensing unit andthe trail behind vehicle is a wagon, or the like, such as indicated inFIGURE 2, and represented generally by reference numeral 93. In thisinstance after the tongue 66 is suitably attached to the cross bar 56,of adapter 65, and link 70 is interconnected between boom and saidtongue the look-out pin 83 is removed thus transforming said link from arigid to a yieldable resilient connection between said boom and tongue.In this instance the position control system of the tractor is utilizedin lieu of the draft control system thereof. Accordingly, handle 51 ismoved in a direction such as to cause walking beam 48 to rotatecounterclockwise and through the link member 46 actuate valve 32 toproduce a lifting of the hitch linkage mechanism and attached tongue 66a distance sufiicient to effect the degree of weight transfer desired,after which the position followup mechanism including interconnectedmembers 52, 53 and 54 will operate to return valve 32 to neutral andthus lock the hydraulic fluid in the lift cylinder circuit in theposition then attained. Now in the event of a change in relativerelationship between the tractor and vehicle, as heretofore discussed,the spring 86 in link becomes yieldable to temporarily relieve orincrease as necessary the degree of weight being transferred, and assoon as this temporary change in relative relationship is passed thesystem returns to normal with the same weight transfer settingheretofore selected being retained. Thus it will be seen that thisarrangement readily accommodates passage over uneven ground and changesin the relative relationship and movement between tractor and trailedvehicle resulting therefrom without having to make other compensatingcorrections or adjustments to the mechanism to accommodate such changes.

It will be evident, also, from the above that when the tractor isequipped to provide lower link sensing and a vehicle is trailedtherebehind, the operation will be identical to that previouslydescribed for the upper link sensing arrangement, since the control forthe weight transfer is by way of the position control system rather thanthe draft or load control system.

What is claimed is:

1. In a tractor having a vertically adjustable hitch linkage forattaching trailed equipment to the tractor including a single upperdraft link and a pair of laterally spaced lower draft links, poweroperated means for lifting, lowering and maintaining a preselectedposition of the linkage, draft control means for said power operatedmeans including a spring assembly loadable in opposite directions from aneutral position and connected with at least one of the links of saidlinkage and operable to measure the draft load imposed thereon byattached trailed equipment and to initiate lifting or lowering of thelinkage to maintain a predetermined draft load and including manuallyoperable means for adjusting said draft control means to determine thedraft load to be maintained on the hitch linkage, and position controlmeans for operating said power operated means to lift and lower thehitch linkage and to maintain a predetermined position thereof andincluding manually operable means for adjusting the predeterminedelevational position of the hitch, the combination therewith,comprising: adapter means mounted on said hitch linkage and operativefor attaching trailed equipment and transferring a part of the weight ofattached trailed equipment to the tractor to increase the tractionthereof, said adapter means comprising a frame pivotally mounted formovement in a vertical plane about an axis extending between trailingends of the lower draft links of said bitch and including aload-attaching portion that extends below the pivotal axis of the frame,said adapter means further having a member extending outwardly therefromand pivotally mounted for movement in a horizontal plane relative tosaid frame, a tongue member connected between said load-attachingportion of the frame and attached trailed equipment and constructed andarranged to permit attached trailed equipment to swing relative to thetractor in vertical and horizontal planes, and force-transmitting meansconnecting the tongue to said outwardly extending member comprisingresilient means adapted to be selectively locked or unlocked so as to berespectively rigid or resilient and thus operative respective to controlin one instance by the draft control means and in another instance bythe position control means for transmitting a lifting force from thehitch linkage to attached trailed equipment.

2,970,653 2/1961 Hershman 172-465 Brudnak et al 172-9 Faure 172-9 Clarke1729 Hansmann 17210 Bunting 1729 Bunting et a1. 1721O Bunting et a1.1729 US. Cl. X.R.

